辐射沙洲海域浮游动物特征和吕泗渔场的成因分析

为探讨辐射沙洲海域浮游动物饵料变化规律和吕泗渔场的形成机制,于2012年5月(春季)和2012年9月(秋季)采集了苏北浅滩辐射沙洲核心海域浮游动物样品,通过聚集强度、方差贡献、优势度及逐步回归等指标和方法,分析了苏北浅滩浮游动物时空分布与辐射沙洲地形等环境因子的关系。结果显示:春、秋两季,浮游动物的生物量和丰度分布均表现出沙脊水域高于潮沟水域,且存在明显的季节差异。春季不同水域平均生物量分别为沙脊水域606.63 mg/m³、沟底水域428 mg/m³、沟口水域为178.55 mg/m³,秋季为沙脊水域208.01 mg/m³、沟底水域181.30 mg/m³、沟口水域60.47 mg/m³;春季不同水域平均丰度分别为沙脊水域560.76个/m³、沟底水域389.39个/m³、沟口水域161.28个/m³,秋季为沙脊水域184.15个/m³、沟底水域56.42个/m³、沟口水域112.14个/m³。春、秋季桡足类均占绝对优势。研究表明:研究水域浮游动物分布特征与地形和潮波系统有关,沙脊水域的浮游动物数量高于潮沟水域,其原因一方面是潮沟地形造成沙脊上流速较小,潮沟中流速较大,另一方面东海前进潮波与南黄海旋转潮在沙脊线附近汇合,导致处于交汇处的沙脊水域水动力较弱,因此浮游动物容易在沙脊水域集聚和摄食。苏北浅滩潮沟系统海域的饵料水平远高于其他水域,其优势种群主体为桡足类,是经济鱼类主要的饵料组分,这是吕泗渔场成为我国著名渔场的重要环境因素。

Causal analysis of distribution pattern of zooplankton in radial sand ridge area of Jiangsu shoal and Lvsi Fishing Ground

The distribution of zooplankton in the area of radiate sand ridges in north Jiangsu shoal was investigated during May and September in 2012.The relationship between the distribution of zooplankton,topography and some other environmental factors were analyzed by using indicators and methods of gathering strength,variance contribution,dominance index,stepwise regression,etc..The results showed that both of the biomass and abundance of zooplankton have obvious seasonal variation.Spatially,the quantity of zooplankton was higher in sand ridges than that in tidal creeks.In spring,the average biomass of different areas were 606.63 mg/m³(sand ridges),428.00 mg/m³(shallow tidal creeks)and 178.55 mg/m³(deep tidal creeks).The average abundance were 560.76 ind/m³(sand ridges),389.39 ind/m³(shallow tidal creeks)and 161.28 ind/m³(deep tidal creeks).However,in autumn,the average biomass of different areas were 208.01 mg/m³(sand ridges),181.30 mg/m³(shallow tidal creeks)and 60.47 mg/m³(deep tidal creeks).And the average abundance were 184.15 ind/m³(sand ridges),56.42 ind/m³(shallow tidal creeks)and 112.14 ind/m³(deep tidal creeks).The study showed that the Copepods was predominant species in two seasons.The research indicated that the distribution of zooplankton was associated with topography and tidal waves in the north Jiangsu shoal.Some reasons can explain it.Firstly,the water velocity was influenced by the topography,where the water velocity was higher in sand ridges than tidal creeks.Secondly,the East China Sea tidal wave and the South Yellow Sea tidal wave converged in north Jiangsu shoal.Sediment can be deposited easily in low flow velocity water,and upwelling waters brought a wealth of nutrients.It would be beneficial to the aggregation and feed of zooplankton,which lead to high biomass and abundance of zooplankton in sand ridges.The dominant species tend to be highly aggregated,which contributed to the main component of economic fishes' bait.The food availability and quality of north Jiangsu shoal were higher than other water areas,which played a crucial role in the formation of Lüsi Fishing Ground.